CN203434996U - Input/output receiver and associated system - Google Patents

Abstract

A serial input/output method and a receiver are provided. The receiver includes a receiving part which receives analog differential serial input and samples the input to provide data and error signals, an equalization feedback loop which responds to the data and the error signals to adjust the receiver part, a phase feedback device which is separated from the equalization feedback loop to provide phase errors, and a clock data recovery module which is coupled to receive the phase errors to execute timing recovery used for the receiver part which is independent of equalization feedback so as to adjust sampling.

Description

I/O receiver and the system being associated

Technical field

The utility model relates generally to data processing technique, more specifically, and the system that relates to I/O receiver and be associated.

Background technology

In the past decade, engineers stably increases the needs that data rate that high-speed serial I across various industry standards/O realizes meets the growth of business and consumer's application always.Current product is for the data rate of 8-10 gigabit per second.It is usually complicated and challenging that receiver clock in this data rate and data are recovered framework.Framework is evolving to improve performance and power always.In the industry cycle widely used prior art has two class receiver architectures: as the clock and data recovery with Alexander phase-detection and two subrates samplings shown at prior art Fig. 1, and as at prior art Fig. 2 shown in the symbol rate timing recovery method of use Mueller-M ü ller principle.

The receiver architecture that uses Alexander type regularly to recover has been realized two subrate samplings as shown in Figure 1.It is typically by forming with lower member: high-gain, high bandwidth CTLE(linear equalization continuous time amplifier), two phase place interpolation device (PI), data and edge sample device, and digital CDR(clock and data recovery) piece.Differential input signal RXP and RXN are amplified by CTLE, and its output (outp and outn) driving data sampler and edge sample device the two.Two phase place interpolation device mixing PLL input clock, and output quantizes to CTLE the centre of (UI) in unit gap to generate in-phase clock (clki) for data sampler, and generate orthogonal clock (clkq) for edge sample device and come the transform instances place of in unit gap (UI) to quantize CTLE to export.Put into coupling clock buffer (CLKBUF) and build the Clock Tree that is respectively used to clki and clkq.Sampler typically catches CTLE output with rising edge and the drop edge of clock, wherein d0 is the even bit data sampling in clki rising edge, d1 is the odd bits data sampling in clki drop edge, e0 is the even bit edge sample in clkq rising edge, and e1 is the odd bits edge sample in clkq drop edge.Data sampler also generating digital clock (clk) is bound d0, d1, e0, e1 to drive downstream logic.Numeral CDR piece usage data and edge sample are formulated Alexander phase-detection, and phase error output drives digital loop filter.Loop filter output is encoded as phase interpolator DAC(digital to analog converter) control routine (pi_dac1 and pi_dac2), to adjust respectively the clock phase of two phase place interpolation device.The receiver architecture that uses Alexander type regularly to recover is in the industry cycle used widely, but when data rate keeps increasing, it faces the design challenge day by day increasing, because the 2X sample requirement of Alexander phase-detection makes power efficiency become less.

Use the symbol rate of Mueller-M ü ller principle regularly to recover to have obtained more attraction in nearest serial i/O receiver architecture.This receiver is typically by forming with lower member: have high-gain, high bandwidth CTLE(linear equalization continuous time amplifier that automatic gain is controlled (AGC)), there is the DFE(decision feedback equalizer of data and error sampler, voltage or current integration type), and the clock-data recovery circuit based on Mueller-M ü ller algorithm.

Two the samplings (centre of unit gap and edge) required with " data-edge " based on CDR are compared, Mueller-M ü ller CDR algorithm need to be sampled at per unit interval (UI), thereby needs the sampler of smaller amounts and have more efficient area and power efficiency.This framework that uses CTLE, DFE, Mueller-M ü ller CDR algorithm and the lowest mean square (LMS) based on optimizing with AGC has been shown in Fig. 2.CTLE amplifies differential input signal RXP and RXN, and its output (outp and outn) drives decision feedback equalizer (DFE).Single-phase interpolation device mixing PLL input clock also generates in-phase clock output (clki).Clki is distributed equalizer output (vxp and vxn) is quantified as to data and fault bit by the Clock Tree network (CLKBUF) for sampler.The further generating digital clock of sampler (clk) is bound data and the error for downstream logic.Numeral CDR piece usage data and fault bit are formulated Mueller-M ü ller algorithm, and phase error output drives digital loop filter.Loop filter output is encoded as phase interpolator DAC control routine (pi_dac1), to adjust the clock phase of phase interpolator.Meanwhile, digital LMS piece utilizes identical data and fault bit are adjusted the gain of CTLE and by control signal DFECoef, are adjusted balanced by control signal AGCCoef.Optimization device is designed to minimize the voltage mean square error of DFE difference output (vxp-vxn) to the reference voltage level of error sampler.In a word, Mueller-M ü ller CDR loop and the AGC-DFE loop aligned sample based on being produced by DFE is assembled simultaneously, causes CDR and DFE loop to interact.This framework can be referred to as " balanced MMCDR ".Intrinsic loop interaction energy negatively affects performance and the stability of this balanced MM CDR receiver architecture.

Utility model content

According to a scheme of the present utility model, a kind of I/O receiver is disclosed, comprising: for receiving analog differential serial input and described input being sampled to provide the receiver section of at least one signal; In response at least one signal, adjust the balanced feedback loop of described receiver section; Separated so that the phase feedback device of phase error to be provided with described balanced feedback loop; And be coupled to receive described phase error and carry out the clock and data recovery piece that the timing for described receiver section recovers.

Described phase feedback device comprises that independently integrator and sampler are to offer lack of balance signal described clock and data recovery piece, and wherein, described signal and lack of balance signal are data and error signal.

Described receiver section also comprises linear equalization amplifier continuous time that is coupled to receive described difference serial analog input.

Described amplifier receives automatic gain control coefficient via described balanced feedback loop.

Described receiver section also comprises and the decision feedback equalizer of the output coupling of described amplifier, and wherein, described decision feedback equalizer receives decision feedback equalizer coefficient and provides data and error signal via described balanced feedback loop.

Described balanced feedback loop comprises the least mean-square error optimization piece that receives described data and error signal from described decision feedback equalizer, and described automatic gain control coefrficient and decision feedback equalizer coefficient are provided.

The described independently integrator of described phase feedback device and the output of sampler and described amplifier coupling.

Described phase feedback device comprises the digital estimator of the numeral of phase error being estimated to offer described clock and data recovery piece.

Described receiver section also comprises linear equalization amplifier continuous time that is coupled to receive described difference serial analog input, and wherein said amplifier receives automatic gain control coefficient via described balanced feedback loop.

Described receiver section also comprises the decision feedback equalizer with described amplifier output coupling, wherein, described decision feedback equalizer receives decision feedback equalizer coefficient and provides data and error signal via described feedback loop, and wherein, described balanced feedback loop comprises for receive the least mean-square error piece of described data and error signal from described decision feedback equalizer, and described automatic gain control coefrficient and decision feedback equalizer coefficient is provided.

According to another program of the present utility model, a kind of I/O receiver is disclosed, comprising: for receiving analog differential serial input and described input being sampled to provide the receiver section of data and error signal; In response to described data and error signal, adjust the first feedback loop of described receiver section; Separated with described the first feedback loop and respond the second feedback loop of the phase place of described difference serial input signals; And be coupled to carry out with described the second feedback loop the clock and data recovery piece regularly recovering.

Described receiver section also comprises linear equalization amplifier continuous time that is coupled to receive described difference serial analog input, and wherein, described amplifier receives automatic gain control coefficient via described the first feedback loop.

Described receiver section also comprises and the decision feedback equalizer of the output coupling of described amplifier, and wherein, described decision feedback equalizer receives decision feedback equalizer coefficient and provides data and error signal via described the first feedback loop.

Described receiver section also comprises the lack of balance device with the output coupling of described amplifier, and wherein, described lack of balance device is identical with described decision feedback equalizer and do not receive the circuit of decision feedback equalizer coefficient.

The two comprises respectively the capacitive load that differential feedback electric current and common mode current is carried out to integration described decision feedback equalizer and described lack of balance device.

Described receiver section comprises the integrator separated with described decision feedback equalizer and sampler, so that lack of balance data and error signal are offered to described clock and data recovery piece.

Described the first feedback loop comprises the least mean-square error optimization piece that receives described data and error signal from described decision feedback equalizer, and described automatic gain control coefrficient and decision feedback equalizer coefficient are provided.

According to a scheme more of the present utility model, a kind of I/O receiver is disclosed, comprising: for receiving analog differential serial input and described input being sampled to provide the receiver section of data and error signal; In response to described data and error signal, adjust the balanced feedback loop of described receiver section; In response to described data and error signal, carry out the phase place estimator of estimating phase error; And with the clock and data recovery piece of described phase place estimator coupling, with the timing of carrying out for described receiver section, recover.

Described receiver section also comprises decision feedback equalizer, and it receives decision feedback equalizer coefficient and receive timing signal from clock and data recovery piece via described balanced feedback loop.

According to another scheme of the present utility model, a kind of system is disclosed, comprising: the first equipment; The second equipment; And the I/O receiver being coupled between described the first equipment and described the second equipment, serial i/O receiver comprises: for receiving analog differential serial input and described input being sampled to provide the receiver section of data and error signal; In response to described data and error signal, adjust the balanced feedback loop of described receiver section; Separated so that the phase feedback device of phase error to be provided with described balanced feedback loop; And be coupled to receive described phase error and carry out the clock and data recovery piece that the timing for described receiver section recovers.

Described the first equipment is included in the processor forming on semiconductor chip.

Described the second equipment comprises the figure module that described semiconductor chip is supported.

Described the second equipment comprises chipset, inserts at least one in card and memory three.

Described the first equipment comprises with lower at least one: processor, chipset, insertion card, figure module and memory, and wherein, described the second equipment comprises with lower at least one: processor, chipset, insertion card, figure module and memory.

Accompanying drawing explanation

Fig. 1 is the prior art figure that uses the clock and data recovery system of Alexander phase-detection and 2X sampling.

Fig. 2 is the prior art figure that uses the clock and data recovery system of Mueller-M ü ller phase-detection and symbol rate sampling.

Fig. 3 is the independently equalizer and the regularly schematic block diagram of the high speed serialization receiver of feedback loop of having according to exemplary embodiment.

Fig. 4 be according to exemplary embodiment can be with the circuit diagram balanced and decision feedback equalizer that lack of balance pattern operate for realizing.

Fig. 5 shows the assembled pulse response of observing in the output of signal amplifier according to exemplary embodiment.

Fig. 6 is according to the schematic block diagram of the high speed serialization receiver with equalizer feedback loop and digit phase estimation of exemplary embodiment.

Fig. 7 shows according to the exemplary timing diagram of the clock for equalizer output and recovery of exemplary embodiment.

Fig. 8 is the independently equalizer and the regularly block flow diagram of the high speed serialization receiver of feedback loop of having according to exemplary embodiment.

Fig. 9 is according to the block flow diagram of the high speed serialization receiver with equalizer feedback loop and digit phase estimation of exemplary embodiment.

Figure 10 is the block diagram illustrating according to each embodiment of the use serial receiver of exemplary embodiment.

Embodiment

In the following description, with reference to the accompanying drawing of the part as in describing, and by being shown, the embodiment that specifically can implement represents therein.With enough details, describe these embodiment, to enable those skilled in the art to implement the present invention, and should understand the embodiment that can use other, and in the situation that not departing from the scope of the invention, can make structure, logic and electric change.Thereby the exemplary embodiment of following description is not for restriction object, and scope of the present invention is defined by the claim of enclosing.

In one embodiment, function described herein or algorithm can be realized with the combination of semiconductor equipment or hardware and firmware.In addition, this function is corresponding to module, and described module is the software being stored in memory device, hardware, firmware or its combination in any.Can by one or more modules, carry out a plurality of functions as required, and the embodiment describing is only example.Can for example, with serial i/O receiver, ASIC, the microprocessor of digital signal processor or the equipment that operates in the other types in computer system (, personal computer, server or other computing systems), realize described function or algorithm.

Fig. 3 is the block diagram of realizing the receiver 300 of lack of balance clock recovery.Receiver 300 comprises the first receiver section that receives serial input signals.In one embodiment, the first receiver section is processed serial input signals, and can be with analog circuit and with digital unit, realize the circuit of processing input signal alternatively.First can be described as analog receiver part (RXANA) piece 310 of being indicated by dotted line.Piece 310 and second portion coupling, this second portion is called as digital receiver part (RXDIG) piece 315 of also indicating with dotted line similarly.Usually, piece 310 treatment of simulated input signals and signal is converted to the digital signal of being processed by piece 315.Thetimer piece 320 of being indicated by dotted line in one embodiment, offers piece 310 by timing signal.In certain embodiments,timer piece 320 can also offer timing signal piece 315.

At input terminal, 325,327 places offer linear equalization amplifier continuous time (CLTE) 330 by analog differential serial input signals.In one embodiment,amplifier 330 has thevariable gain input 332 that receives automatic gain control coefficient (AGCCoef).Amplifier 330 offers decision feedback equalizer (DFE) 340 by differential signal in output 335,337.Decision feedback equalizer coefficient (DFECoef) by 342 places is adjustedequalizer 340.

Analog differential input signal is variant on voltage, and it depends on the voltage difference between differential signal and is expressed as numeral " 1 " or digital " 0 ".In one embodiment,equalizer 340 comprisesintegrator 345, and it carries out the integration of selected time quantum to the difference in the differential signal fromcircuit 335 and 337.Selected time quantum depend on the single numerical value represent receiving input differential signal time span and change, during signal that selected time quantum will recover to receive from transmission substantially the signal strength signal intensity of loss.For example, in one embodiment, the signal receiving can derive from the image card with system board coupling, and can be received by the processor on system board.The signal of some transmission is lost because of the noise of resistance and disperse and introducing when signal advances to receiver 300 along path.

Once 345 pairs of differential signals of integrator carry out integration, differential signal is for example offered to sampler 350, for the selected collection of signal relative reference (reference voltage) is sampled.In one embodiment, there are two data samplers and four error samplers.

In one embodiment,data sampler 350 determine corresponding to the difference in the integrated voltage between the signal of each logical value (integrated voltage) be higher than or lower than 0mV.Oncircuit 352, provide digital data signal, be wherein greater than zero difference and can be expressed as " 1 " and can be expressed as " 0 " lower than zero difference.

In one embodiment,error sampler 350 determine corresponding to the difference in the integrated voltage between the signal of each logical value be higher than or lower than threshold voltage level, for example +/-100mV, +/-150mV, maybe can depend on other set point values of realizing details in each embodiment.Oncircuit 354, provide digital error signal, the difference that is wherein greater than threshold value can be expressed as " 1 " and can be expressed as " 0 " lower than the difference of threshold value.

Logic level for data and control information in each embodiment can be contrary, maybe can encode by various schemes, and it is contrary making at different time logical level.

Data 352 anderror 354 signals are offered to lowest mean square (LMS)error block 360, its minimum error also offers respectivelyequalizer 340 andamplifier 330 by digital feedbackequalization device coefficient 342 and automaticgain control coefrficient 332, forms decision feedback equalizer loop to adjust the parameter of analog receiver piece 310.Equalizer 340 comprises thefeedback block 351 that receivesfeedback equalizer coefficient 342 anddata 352, and provides feedback with the input summation atsampler 350.

LMSpiece 360 also offers signal serial-to-parallel (S2P) and acts on behalf of 362, and receiver data (RxData) output signal is provided onparallel output circuit 363, to complete simulation serial input signals to the conversion of digital parallel output signal.

Clock anddata recovery piece 375 offers the signal that is labeled as PICode thedigital control circuit 380 that is labeled as PIDIG on circuit 377.Digital control circuit 380 offers phase interpolator (PI)piece 385 by thecontrol signal 383 that is labeled as pi_dac code, it is according to pi_dac code mixing pll clock (ClkPLLI and ClkPLLQ), and theclock signal 387 that is labeled as piclk is offered toclock generator 390 clock signal clkhs392 is offered to the analog circuit that comprises independent feedback lack of balance device 364 andequalizer 340, and clock signal clkdig394 is offered to the digital circuit that comprises CDR375, S2P362 and LMS360.

In one embodiment, be provided with and comprise integrator 365, sampler 367 and feed back 368 independent feedback lack of balance device piece 364, and independent feedback lack of balance device piece 364 is coupled to amplifier 330outputs 335 and 337.Independent integral device 365 and sampler 367 produce respectively numerical data and digital error signal on circuit 369 and 371, are labeled as lack of balance data (uneqdata) and lack of balance error (uneqerror).Data separating on these signals and 352 and 354, and without the adjustment being provided tointegrator 345 andsampler 350 by feedback loop is provided.Uneqdata and uneqerror signal are offered to clock anddata recovery piece 375, and clock anddata recovery piece 375 has been realized the Mueller-M ü ller algorithm for clock and data recovery.When previously used combination feedback loop may cause loop to interact, the separation of feedback loop has in certain embodiments improved the stability of receiver 300.

The present invention is definite: provide identical data and the error signal as former, done carry out that LMS is balanced to be adjusted and clock and data recovery (CDR) may cause less desirable interaction between receiver decision feedback equalizer loop and symbol rate are regularly recovered.Become highly significant link training is had a negative impact of this interaction energy.Some difficult points of observing comprise by guiding (boot-to-boot) variation, link width degenerates and link failure to train.

In one embodiment, independent lack of balance device piece 364 can be structurally identical withequalization block 340, except some inputs as shown in Figure 3 reconnect to piece 364.By use same structure in equalizer and lack of balance device, this circuit framework guarantees that internal signal feature (for example constant time lag) mates.Only difference is that the feedback that outputs to sampler input from data removes lack of balance device piece 364.

In one embodiment, 400 in Fig. 4 shows for realizing the circuit of decision feedback equalizer, and described decision feedback equalizer can be used for simulating coupling with equilibrium and the operation of lack of balance pattern ofcorresponding blocks 340 respectively and 364.For simple object, only shown a feedback tap.

According to exemplary embodiment, for the balanced mode operation with corresponding to DFE340, dcm in 405 places indications is set to 1, and the input that is labeled as dodd410, doddb412, deven414 and devenb416 is connected to sampler output, and LMS360 controls DEFCoef342.

According to exemplary embodiment, in order to operate for realizing lack of balance device 364 with lack of balance pattern, dcm405 is set to 0, and dodd410, doddb412, deven414 and devenb416 are tied to logical one, and DFECoef is grounded.

In one embodiment,circuit 400 is used half rate current integration structure.Its input difference is converted to electric current to (vip420 and vin422) by CTLE output voltage.Total current in this input integral stage equals the Isum in the indication of 424 places.Half rate clock ck0 and the ck180 at 428 places at 426 places are directed to the electric current of conversion respectively evennumber 430 andodd number 432 paths, and control the charge or discharge of corresponding capacitive load 434.Form with differential feedback electric current I fbkp436 and Ifbkn438 realizes equilibrium.When the summation of Ifbkp and Ifbkn is constant, by DFECoef, determined their difference.Be similar to the input integral stage, half rate clock ck0 and the ck180 at 428 places at 426 places are directed to feedback current respectively even number and odd number path.During balanced mode, by dodd410, doddb412, deven414 and devenb416, controlled, differential feedback electric current I fbkp and Ifbkn are incorporated incapacitive load 434, generate respectively balanced output vep440, ven442, vop444 and von446.During lack of balance pattern, remove differential feedback, but common-mode electric current is still incorporated incapacitive load 434, to generate respectively output vep440, ven442, vop444 and the von446 of lack of balance.Getting around sampler data exports to avoid in integration unnecessary conversion in period.

Use the performance difference that may occur while helping be minimized in the different circuit of assembling for equalizer and the same circuits of lack of balance device.In one embodiment, can field-effect transistors (for example p-type or N-shaped transistor) realize circuit 400.In another embodiment, can use bipolar transistor.Current integration structure is different from realizing in this embodiment, can design in another embodiment the voltage mode structure of using ohmic load.From use in this embodiment PMOS input and exchange to different, another embodiment can be used to be had NMOS input and exchanges right duel topology.Half rate clock scheme is different from using in this embodiment, can even number and odd number path of integration be expanded to four phase integral paths with Quad Data Rate clock scheme in another embodiment.

Receiver 300 is shown lack of balance Mueller-M ü ller CDR or simple UneqMM framework in concept rank.Lack of balance device 364 is sampled as uneqdata and uneqerror by the output of amplifier 330.Then by uneqdata and uneqerror, drive uneqMM CDR375, still by balanced DFE340 output, drive LMS360 simultaneously.Thereby minimized loop interaction.In one embodiment, in balanced MM CDR equation, there is skew, and in input data, introduce this skew while being uncorrelated by DFE340 the first tap coefficient,

E{φ'(n)}=w₀E{φ(n)}-w₁.…(1)

φ is the phase error function of unEqMM CDR, and φ ' is the phase error function of EqMM CDR, w₀aGC gain, w₁be DEF the first tap feedback, E{} represents statistical average, and hypothesis input data are incoherent.

Fig. 5 is according to the visable representation of the balanced regularly phase deviation that recovery is introduced of being shown by equation (1) of one or more embodiment.X axle represents the time, and y axle represents voltage.In one embodiment, Fig. 5 shows in the mode of amplitude relative time the interconnection that comprises of observing at CTLE330 place, and the impulse response of the combination of silicon encapsulation and CTLE gain path.The response illustrating is quite symmetrical, and provides indication to come for lack of balance Mueller-M ü ller sampled point 515 and balanced Mueller-M ü ller sampled point 530 above.This performance demonstrates along with data rate increases, 10 to 20 picoseconds or still less the difference in sampling time of time can cause adverse effect to the performance of receiver.

In one embodiment, Mueller-M ü ller CDR formulates phase error function, and described function ratio is impulse response rank 1UI(mono-unit gap before sampled point-integrate the in one embodiment time durations of sampling) and sampled point after 1UI between voltage differences.In balanced Mueller-M ü ller CDR before, the balanced offset voltage of introducing in phase error function.Although phase error function is arranged to zero after convergence in average meaning, this offset voltage makes invocation point 525 and 535 differences.The difference of the voltage between point 525 and 535 is the balanced feedback voltage of DFE.According to some embodiment, as long as input data are incoherent, no matter whether other taps exist, this feedback voltage is determined by DFE the first tap completely.The skew between point 525 and 535 of balanced Mueller-M ü ller CDR pushes away sampled point 530 peak value of impulse response, and it may meet with signal to noise ratio (snr) and decline in integrator input.SNR declines and even become more remarkable in the stronger balanced higher loss channel of needs, thereby causes sampled point to depart from significantly the peak value of impulse response.According to embodiments of the invention, in lack of balance Mueller-M ü ller CDR, because do not have equilibrium to be applied to the impulse response in Fig. 5, or the equilibrium applying removed before phase-detection, so phase error function converges to zero in average meaning, makes invocation point 510 and 520 have equal amplitude.Therefore, sampled point 515 has the peak value of the impulse response of highest signal to noise ratio.

In essence, receiver 300 is direct realizations of the concept of separated feedback loop, makes not have portfolio effect to add the signal path using in clock recovery loop.Receiver 300 uses other data and error sampler sum-product intergrator.Extra circuit carrying further silicon power and the consumption of area.When using multi-line, consumption is doubled, and this can cause larger chip size.

Fig. 6 shows with digital method and estimates lack of balance MM phase error and without thereplacement receiver 600 of other sampler circuit.Many parts can be identical with the parts that use in Fig. 3, and suitably locating to providesimilar label.Receiver 600 comprises the first clock, analog receiver (RXANA)clock 610 that for example dotted line is indicated, and itself and second clock are coupled, and second clock is for example digital receiver (RXDIG)clock 615 of also indicating with dottedline.Piece 610 and 615 can be realized with analog-and digital-parts in each embodiment.Usually,piece 610 treatment of simulated input signals signal is converted to the digital signal thatpiece 615 is processed.In one embodiment, thetimer piece 320 of dotted line indication offerspiece 610 by timing signal 392.In certain embodiments,timer piece 320 also offersclock 615 by timingsignal 394.

In the receiver 300 in Fig. 3, at input terminal, 325,327 places offer linear equalization amplifier continuous time (CTLE) 330 by analog differential serial input signals.In one embodiment,amplifier 330 has the variable gain input 322 that receives automatic gain control coefficient (AGCCoef).Amplifier 330 offersdecision feedback equalizer 340 by differential signaloutput 335,337.Equalizer 340 also receives decision feedback equalizer coefficient (DFECoef) at 342 places viafeedback block 351.

In one embodiment,equalizer 340 comprisesintegrator 345,sampler 350 andfeedback block 351, so that data and error signal to be provided oncircuit 352 and 354.Data 352 anderror 354 signals are offered to lowest mean square (LMS)error optimization piece 360, optimizepiece 360 minimum error and digital feedbackequalization device coefficient 342 and automaticgain control coefrficient 332 are offered respectively toequalizer 340 andamplifier 330, forming decision feedback equalizer loop.

Inreceiver 600, also the data oncircuit 352 and 354 and error signal are offered to thedigital estimator piece 620 being inserted in piece 615.In one embodiment,numeral estimator piece 620 estimates to offer clock anddata recovery piece 375 by the numeral of phase error, described clock anddata recovery piece 375 is identical with the simulation lack of balance MM of receiver 300 in average meaning, but the excess power and the area consumption that do not provide other analog circuit to create independent loop.

In one embodiment,digital estimator piece 620 has been realized the method for following estimating phase error.The estimation of unEqMM phase error is defined as

$w_0\widehat{\mathrm{\&phi;}}\left(n\right)={\mathrm{\&phi;}}^{\&prime;}\left(n\right)+(1-E\{d_n{d}_{n-2}\left\}\right){\mathrm{<figure-callout\; label="w"\; filenames="HDA00003073045400051.png"\; state="\{\{state\}\}">w</figure-callout>}}_1.\&CenterDot;\&CenterDot;\&CenterDot;\left(2\right)$

The unEqMM phase error of estimating is identical with simulation lack of balance MM in statistical average meaning,

$E\left\{\widehat{\mathrm{\&phi;}}\left(n\right)\right\}=E\left\{\mathrm{\&phi;}\left(n\right)\right\}.\&CenterDot;\&CenterDot;\&CenterDot;\left(3\right)$

If suppose that input data are incoherent,digital estimator 620 can be reduced to

$w_0\widehat{\mathrm{\&phi;}}={\mathrm{\&phi;}}^{\&prime;}\left(n\right)+{\mathrm{<figure-callout\; label="w"\; filenames="HDA00003073045400051.png"\; state="\{\{state\}\}">w</figure-callout>}}_1.\&CenterDot;\&CenterDot;\&CenterDot;\left(4\right)$

be the estimation amount of the phase error function of lack of balance CDR, simultaneously φ represents original uneqMM phase error function, and φ ' is the phase error function of balanced CDR.W₀represent AGC gain, w₁represent DFE the first tap feedback, d_nbe input data, and E{} represent statistical average operator.

In certain embodiments,receiver 300 and 600 has improved the link stability of high-speed serial I/O.They also promote receiver to work under default and coefficient at the terminal transmitter of wider scope, further contribute to electric profit raising, link stability and performance.Be used for the more transmitter with many tap equalization of high data rate and there is intrinsic inexactness in balanced rank.The stalwartness operation with wider equalizing coefficient scope has improved each supplier of graphics card and the interoperability between other contacts partner.

Fig. 7 is according to the timing diagram 700 of the receiver 200 of some embodiment andreceiver 600, shows the phase alignment of lack of balance Mueller-M ü ller clock and data recovery.Usually at 710 place's indication lack of balance clock and data recovery signals, and at 715 place's indication balanced clock data restoring signals.X axle represents the time, and y axle represents voltage.Rxp andrxn waveform 730 are the inputs of receiver difference.Outp andoutn waveform 740 are the CTLE difference output that drives equalizer block 340 interior integrators.Ck0 andck180 waveform 750 are to adopt clock.The phase place of ck0 andck180 clock 750 is adjusted by lack of balance Mueller-M ü ller clock recovery loop.Vop, von, vep andven waveform 760 are the integrator output in piece 340.In one embodiment, the clock signal of indicating at 750 places of lack of balance clock and data recovery is aimed atCTLE output signal 740, thereby clock signal changes the zero crossing that approaches CTLE output signal.This permission integration in phase catches the complete unit gap (UI) of receiver input signal, as shown inshadow region 770.

But, as shown in 715, in the equalizing circuit of prior art,clock signal 755 significantly withCTLE output signal 740 out-phase, only cause integration a part of electric current UI (as shown in shadow region 775), and reduced artificially signal to noise ratio in integrator input.In certain embodiments, balanced feedback has been introduced the misalignment inclock phase 755 according to equation (1), and this may become stronger in higher loss channel.Stronger equilibrium feedback has further increased phase place misalignment, and this even may trigger higher equilibrium feedback conversely.This balanced clock restore circuit likely produces the bit error rate (BER) of link stability problem and Geng Gao.

Fig. 8 illustrates execution for the block flow diagram of themethod 800 of the lack of balance clock recovery of the serial i/O receiver corresponding to receiver 300.At 810 places, receive analog differential serial input.Signal can be amplified and integration in certain embodiments, and provide data and error signal in 820 samplings.The feedback that is provided as least mean-square error majorized function at 825 places is come balanced or adjusts and sample.827, provide and there is no balanced input, wherein do not carry out feedback equalization the simulation serial differential output of amplifying is sampled.At 830 places, the timing of carrying out for the adjustment sampling phases in 825 and 827 samplings from 827 the sampling input that is independent of feedback is recovered to adjust equilibrium.

Fig. 9 is that execution is for the block flow diagram of themethod 900 of the lack of balance clock recovery of the serial i/O receiver corresponding to receiver 600.Some pieces have identical numbering (comprising piece 810,820 and 825) to provide feedback to carry out equalizing signal with the corresponding blocks in Fig. 8.In addition, dottedline 910 removes balanced and estimation phase place for the equalizing signal utilizing frompiece 820 is shown.In one embodiment, the equalizing signal from 820 being offered topiece 915 comes calculated data associated.The data correlation calculating is combined to remove feedback equalization with the feedback frompiece 825 atpiece 920 places.At 925 places, use from the output ofpiece 920 and the feedback equalization removing and estimate sampling phase error.At 930 places, sampling phase error is offered to piece 930 and carry out regularly recovery to adjust sampling phase, it then offerspiece 820 for sampling with suitable interval.

Figure 10 is the block diagram that the system 1000 of using one or more serial receivers is shown.Serial receiver can be a part for transceiver, and described transceiver comprises for transmitting and receive the circuit of signal on connected in series.System 1000 can be via various connections, to carry out (comprising, for example connected in series) electronic product of any type of coupling unit.Example includes but not limited to, desktop computer, laptop computer, server, work station, smart phone, panel computer, and many other equipment.System 1000 realizes method disclosed herein and can be SOC (system on a chip) (SOC) equipment.

In one embodiment, system 1000 comprises a plurality of processors that contain 1010 and 1020, and the logic class that wherein processor 1010 has is similar to or is same as the logic of processor 1020.In one embodiment, processor 1010 and 1020 comprises memory control hub (MCH), and it is operationally carried out and makes the processor can access storage module 1015 and 1025 and the function that communicates with.In one embodiment, system 1000 comprises figure module (GFx) 1030, additional card (AIC) 1040, and chipset module 1050.In one embodiment, processor 1010 and 1020 comprises the serial receiver 300 of Fig. 3 and thereceiver 600 of Fig. 6.In one embodiment, according to I/O communication protocol, such as fast path interconnection (QPI), direct media interface (DMI), peripheral unit connected high-speed (PCIe) interface, the point-to-point serial line interface of FB-DIMM etc., processor 1010 and 1020 use receivers 300 andreceiver 600 communicate with one another, and communicate with memory module 1015 and 1025, with GFx module 1030 with AIC1040 communicates, communicate on interface 1011,1021,1016,1026,1031,1041 and 1052 with chipset 1050.

In one embodiment, chipset 1050 comprises the serial receiver 300 of Fig. 3 and thereceiver 600 of Fig. 6.In one embodiment, chipset 1050 is used receiver 300 to be connected with 1020 with processor 1010 with 1052 via I/O interface 1051 with receiver 600.In one embodiment, chipset 1050 makes processor 1010 and 1020 can be connected to other modules in system 1000.In one embodiment, chipset 1050 use receivers 300 andreceiver 600 communicate with display device 1060, mass-memory unit 1070 and other I/O equipment 1080 etc.

In one embodiment, display device 1060 comprises the serial receiver 300 of Fig. 3 and thereceiver 600 of Fig. 6.In one embodiment, display device 1060 communicates via interface 1061 and chipset.In one embodiment, display 1060 includes but not limited to, liquid crystal display (LCD), plasma, cathode ray tube (CRT) display, or any other forms of visual display device.

In one embodiment, mass-memory unit 1070 includes but not limited to, solid state hard disc, hard disk drive, USB flash drive, or any other forms of computer data storage medium.In one embodiment, other I/O equipment comprises network interface, USB (USB) interface, peripheral unit connected high-speed (PCIe) interface, and/or the interface of other suitable types arbitrarily.In one embodiment, can in serial i/O interface 1071 and 1081, with the receiver 300 of Fig. 3 and thereceiver 600 of Fig. 6, be based upon the communication between chipset, storage and other equipment.

Although module shown in Figure 10 is plotted as the autonomous block in system 1000, some the performed functions in these pieces can be integrated in single semiconductor circuit and maybe can realize with two or more independently integrated circuits.For example, processor 1010,1020 and chipset 1050 can be merged into single SOC.In one embodiment, system 1000 can comprise more than two processors in another embodiment of the present invention and memory module.

Some examples are described now.The structure of describing in example and method can be for any places in one or more embodiment.

Example 1 can comprise I/O receiver, it comprises the receiver section that receives analog differential serial input and input is sampled to provide at least one signal, respond at least one signal and adjust the balanced feedback loop of receiver section, with the separated phase feedback device that phase error is provided of balanced feedback loop, and be coupled with receiving phase error and carry out the clock and data recovery piece recovering for the timing of receiver section.

Example 2 can comprise the receiver of example 1, and wherein phase feedback device comprises that independently integrator and sampler offer clock and data recovery piece by the signal of lack of balance, and wherein signal and lack of balance signal are data and error signal.Example 3 can comprise the receiver of example 1 or 2, and wherein, receiver section further comprises linear equalization amplifier continuous time that is coupled to receive difference serial analog input.

Example 4 can comprise the receiver of example 3, and wherein amplifier receives automatic gain control coefficient via balanced feedback loop.Example 5 can comprise the receiver of example 3 or 4, wherein receiver section further comprises and the decision feedback equalizer of the output coupling of amplifier, and wherein decision feedback equalizer receives decision feedback equalizer coefficient and provides data and error signal via balanced feedback loop.

Example 6 can comprise the receiver of example 5, and wherein balanced feedback loop comprises that least mean-square error optimization piece receives data and error signal from decision feedback equalizer, and automatic gain control coefrficient and decision feedback equalizer coefficient are provided.

Example 7 can comprise the receiver of example 6, wherein the independently integrator of phase feedback device and the output of sampler and amplifier coupling.Example 8 can comprise the receiver of example 7, and wherein the clock and data recovery based on lack of balance data and error signal is proofreaied and correct the sampling phase migration that decision feedback equalization is introduced:

w₀E{φ(n)}=E{φ′(n)}+w₁

Wherein φ is the phase error function of lack of balance CDR, and φ ' is the phase error function of balanced CDR, w₀aGC gain, w₁be DFE the first tap feedback, and E{} represent statistical average.

Example 9 can comprise the receiver of example 8, wherein, as long as input data are incoherent, no matter whether has other taps, and phase deviation is completely definite by DFE the first tap.Example 10 can comprise in example 1-9 the receiver of any one, and wherein phase feedback device comprises the digital estimator that the numeral estimation of phase error is offered to clock and data recovery piece.Example 11 can comprise the receiver of example 10, and wherein receiver section further comprises linear equalization amplifier continuous time that is coupled to receive difference serial analog input, and wherein amplifier receives automatic gain control coefficient via balanced feedback loop.

Example 12 can comprise the receiver of example 11, wherein receiver section further comprises the decision feedback equalizer with the output coupling of amplifier, wherein decision feedback equalizer receives decision feedback equalizer coefficient and provides data and error signal via feedback loop, and wherein balanced feedback loop comprises the least mean-square error piece that receives data and error signal from decision feedback equalizer, and automatic gain control coefrficient and decision feedback equalizer coefficient are provided.

Example 13 can comprise the receiver of example 12, and wherein digital phase error estimation device is defined as:

$w_0\widehat{\mathrm{\&phi;}}\left(n\right)={\mathrm{\&phi;}}^{\&prime;}\left(n\right)+(1-E\{d_n{d}_{n-2}\left\}\right){\mathrm{<figure-callout\; label="w"\; filenames="HDA00003073045400051.png"\; state="\{\{state\}\}">w</figure-callout>}}_1$

Wherein

be the estimation amount of the phase error function of lack of balance CDR, and φ ' is the phase error function by using equalization data and error signal to formulate, w₀represent AGC gain, w₁represent DFE the first tap feedback, d_nbe input data, and E{} represent statistical average operator.Example can comprise serial i/O receiver, it comprises the receiver section that receives analog differential serial input and input is sampled to provide data and error signal, response data and error signal are adjusted the first feedback loop of receiver section, the second feedback loop of the phase place of and responsive to differential serial input signals separated with the first feedback loop, and be coupled to carry out with the second feedback loop the clock and data recovery piece regularly recovering.

Example 15 can comprise the receiver of example 14, and wherein receiver section also comprises linear equalization amplifier continuous time that is coupled to receive difference serial analog input, and wherein amplifier receives automatic gain control coefficient via the first feedback loop.Example 16 can comprise the receiver of example 15, wherein receiver section further comprises and the decision feedback equalizer of the output coupling of amplifier, and wherein decision feedback equalizer receives decision feedback equalizer coefficient and provides data and error signal via the first feedback loop.

Example 17 can comprise the receiver of example 16, and wherein receiver section also comprises the lack of balance device with the output coupling of amplifier, and wherein lack of balance device is identical with decision feedback equalizer but does not receive the circuit of decision feedback equalizer coefficient.

Example 18 can comprise the receiver of example 17, wherein decision feedback equalizer and lack of balance device the two can comprise capacitive load, respectively differential feedback electric current and common mode current are carried out to integration.Example 19 can comprise the receiver of example 16, and wherein receiver section comprises the integrator separated with decision feedback equalizer and sampler, so that lack of balance data and error signal are offered to clock and data recovery piece.

Example 20 can comprise the receiver of example 19, and wherein the first feedback loop comprises the least mean-square error optimization piece that receives data and error signal from decision feedback equalizer, and automatic gain control coefrficient and decision feedback equalizer coefficient are provided.

Example 20 can comprise serial i/O receiver, it comprises the receiver section that receives analog differential serial input and input is sampled to provide data and error signal, response data and error signal are adjusted the balanced feedback loop of receiver section, response data and error signal are carried out the phase place estimator of estimating phase error, and are coupled to carry out the clock and data recovery piece for the timing recovery of receiver section with phase place estimator.

Example 22 can comprise the receiver of example 21, and wherein receiver section also comprises decision feedback equalizer, to receive decision feedback equalizer coefficient via balanced feedback loop and to receive timing signal from clock and data recovery piece.

Example 23 can comprise a kind of system, this system comprises the first equipment, the second equipment and the serial i/O receiver being coupled between the first equipment and the second equipment, serial i/O receiver comprises the receiver section that receives analog differential serial input and input is sampled to provide data and error signal, response data and error signal are adjusted the balanced feedback loop of receiver section, with the separated phase feedback device that phase error is provided of balanced feedback loop, carry out the clock and data recovery piece for the timing recovery of receiver section with being coupled with receiving phase error.

Example 24 can comprise the system of example 23, and wherein the first equipment is included in the processor forming on semiconductor chip.

Example 25 can comprise the system of example 23 or 24, and wherein the second equipment comprises the figure module that semiconductor chip is supported.Example 26 can comprise the system of example 23 or 24, and wherein the second equipment comprises chipset, inserts at least one in card and memory three.

Example 27 can comprise the system of example 23, wherein the first equipment comprises with lower at least one: processor, chipset, insertion card, figure module and memory, and wherein the second equipment comprises with lower at least one: processor, chipset, insertion card, figure module and memory.Example 28 can comprise a kind of method, the method comprises reception analog differential serial input, to difference serial input, sample to provide data and error signal, provide balanced feedback to adjust sampling, and carry out and regularly recover to adjust sampling for being independent of the sampling of balanced feedback.

Example 29 can comprise the method for example 28, wherein timing recovery is carried out as the function of the independent sample of difference serial input.

Example 30 can comprise the method for example 29, and wherein independent sample provides lack of balance data and the error signal that represents difference serial input.Example 31 can comprise the method for example 30, wherein will regularly recover to carry out to adjust sampling as being independent of the assessment function of the balanced phase error of feeding back.

Although described several embodiment above in detail, other modification is possible.For example, the concrete order shown in the logic flow of drawing does not in the drawings require, or consecutive order reaches the result of expectation.From described flow process, can provide other steps maybe can remove step, and from described system, can add miscellaneous part or remove parts.Other embodiment can be within the scope of claim of enclosing.

Claims (24)

1. an I/O receiver, comprising:

Be used for the receiver section that receives analog differential serial input and described input is sampled to provide at least one signal;

In response at least one signal, adjust the balanced feedback loop of described receiver section;

Separated so that the phase feedback device of phase error to be provided with described balanced feedback loop; And

Be coupled to receive described phase error and carry out the clock and data recovery piece for the timing recovery of described receiver section.

2. receiver according to claim 1, wherein, described phase feedback device comprises that independently integrator and sampler are to offer lack of balance signal described clock and data recovery piece, wherein, described signal and lack of balance signal are data and error signal.

3. receiver according to claim 1 and 2, wherein, described receiver section also comprises linear equalization amplifier continuous time that is coupled to receive described difference serial analog input.

4. receiver according to claim 3, wherein, described amplifier receives automatic gain control coefficient via described balanced feedback loop.

5. receiver according to claim 4, wherein, described receiver section also comprises the decision feedback equalizer with the output coupling of described amplifier, wherein, described decision feedback equalizer receives decision feedback equalizer coefficient and provides data and error signal via described balanced feedback loop.

6. receiver according to claim 5, wherein, described balanced feedback loop comprises the least mean-square error optimization piece that receives described data and error signal from described decision feedback equalizer, and described automatic gain control coefrficient and decision feedback equalizer coefficient are provided.

7. receiver according to claim 6, wherein, the described independently integrator of described phase feedback device and the output of sampler and described amplifier coupling.

8. receiver according to claim 1 and 2, wherein, described phase feedback device comprises the digital estimator of the numeral of phase error being estimated to offer described clock and data recovery piece.

9. receiver according to claim 8, wherein, described receiver section also comprises linear equalization amplifier continuous time that is coupled to receive described difference serial analog input, and wherein said amplifier receives automatic gain control coefficient via described balanced feedback loop.

10. receiver according to claim 9, wherein, described receiver section also comprises the decision feedback equalizer with described amplifier output coupling, wherein, described decision feedback equalizer receives decision feedback equalizer coefficient and provides data and error signal via described feedback loop, and wherein, described balanced feedback loop comprises for receive the least mean-square error piece of described data and error signal from described decision feedback equalizer, and described automatic gain control coefrficient and decision feedback equalizer coefficient is provided.

11. 1 kinds of I/O receivers, comprising:

Be used for the receiver section that receives analog differential serial input and described input is sampled to provide data and error signal;

In response to described data and error signal, adjust the first feedback loop of described receiver section;

Separated with described the first feedback loop and respond the second feedback loop of the phase place of described difference serial input signals; And

Be coupled to carry out with described the second feedback loop the clock and data recovery piece regularly recovering.

12. receivers according to claim 11, wherein, described receiver section also comprises linear equalization amplifier continuous time that is coupled to receive described difference serial analog input, and wherein, described amplifier receives automatic gain control coefficient via described the first feedback loop.

13. receivers according to claim 12, wherein, described receiver section also comprises the decision feedback equalizer with the output coupling of described amplifier, wherein, described decision feedback equalizer receives decision feedback equalizer coefficient and provides data and error signal via described the first feedback loop.

14. receivers according to claim 13, wherein, described receiver section also comprises the lack of balance device with the output coupling of described amplifier, and wherein, described lack of balance device is identical with described decision feedback equalizer and do not receive the circuit of decision feedback equalizer coefficient.

15. receivers according to claim 14, wherein, the two comprises respectively the capacitive load that differential feedback electric current and common mode current is carried out to integration described decision feedback equalizer and described lack of balance device.

16. receivers according to claim 13, wherein, described receiver section comprises the integrator separated with described decision feedback equalizer and sampler, so that lack of balance data and error signal are offered to described clock and data recovery piece.

17. receivers according to claim 16, described the first feedback loop comprises the least mean-square error optimization piece that receives described data and error signal from described decision feedback equalizer, and described automatic gain control coefrficient and decision feedback equalizer coefficient are provided.

18. 1 kinds of I/O receivers, comprising:

Be used for the receiver section that receives analog differential serial input and described input is sampled to provide data and error signal;

In response to described data and error signal, adjust the balanced feedback loop of described receiver section;

In response to described data and error signal, carry out the phase place estimator of estimating phase error; And

With the clock and data recovery piece of described phase place estimator coupling, with the timing of carrying out for described receiver section, recover.

19. receivers according to claim 18, wherein, described receiver section also comprises decision feedback equalizer, it receives decision feedback equalizer coefficient and receives timing signal from clock and data recovery piece via described balanced feedback loop.

20. 1 kinds of systems, comprising:

The first equipment;

The second equipment; And

The I/O receiver being coupled between described the first equipment and described the second equipment, serial i/O receiver comprises:

Be used for the receiver section that receives analog differential serial input and described input is sampled to provide data and error signal;

In response to described data and error signal, adjust the balanced feedback loop of described receiver section;

Separated so that the phase feedback device of phase error to be provided with described balanced feedback loop; And

Be coupled to receive described phase error and carry out the clock and data recovery piece for the timing recovery of described receiver section.

21. systems according to claim 20, wherein, described the first equipment is included in the processor forming on semiconductor chip.

22. according to the system described in claim 20 or 21, and wherein, described the second equipment comprises the figure module that described semiconductor chip is supported.

23. according to the system described in claim 20 or 21, and wherein, described the second equipment comprises chipset, inserts at least one in card and memory three.

24. systems according to claim 20, wherein, described the first equipment comprises with lower at least one: processor, chipset, insertion card, figure module and memory, and wherein, described the second equipment comprises with lower at least one: processor, chipset, insertion card, figure module and memory.

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